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Necessity to Use the True Gravity in Large Scale Atmospheric Modeling
Version 1
: Received: 4 February 2023 / Approved: 7 February 2023 / Online: 7 February 2023 (10:40:58 CET)
How to cite: Chu, P. C. Necessity to Use the True Gravity in Large Scale Atmospheric Modeling. Preprints 2023, 2023020127. https://doi.org/10.20944/preprints202302.0127.v1 Chu, P. C. Necessity to Use the True Gravity in Large Scale Atmospheric Modeling. Preprints 2023, 2023020127. https://doi.org/10.20944/preprints202302.0127.v1
Abstract
Newton’s law of universal gravitation applies between two point-masses. True gravitation of solid Earth is volume integration of gravitation of all point-masses inside the solid Earth on a point-mass in atmosphere. However, in meteorology the Earth “shrinks” into a point-mass located at Earth center with entire Earth mass to identify the Earth gravitation (untrue). Combination of untrue gravitational and centrifugal accelerations gives effective gravity (geff). Combination of true gravitational and centrifugal accelerations leads to true gravity (g). The true gravity g minus the effective gravity geff is the gravity disturbance vector, δg = g – geff. With the true gravity g used in the basic equations, seven non-dimensional numbers are proposed to identify the importance of δg versus traditional forcing terms such as horizontal pressure gradient force and Coriolis force. These non-dimensional numbers are calculated from two publicly available datasets with the geoid undulation (N) from the static gravity field model EIGEN-6C4 and long-term mean geopotential height (Z), wind velocity (u, v), and temperature (Ta) at 12 pressure levels in troposphere from the NCEP/NCAR reanalyzed climatology. The results demonstrate δg nonnegligible in hydrostatic equilibrium, geostrophic wind, geostrophic vorticity, Ekman pumping, Q vector, and Omega equation, but negligible in thermal wind relation.
Keywords
true gravity; effective gravity; gravity disturbance vector; geoid undulation; gravity field mode EIGEN-6C4
Subject
Environmental and Earth Sciences, Atmospheric Science and Meteorology
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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